Biological motion stimuli, depicted as orthographically projected stick-figure walkers (SFWs), do not contain any information about their orientation in depth: A fronto-parallel projection of a SFW facing the viewer is the same as a facing-away projection. Despite this depth-ambiguity, observers tend to interpret SFWs as facing the viewer more often (Vanrie et al., 2004). Some researchers have speculated that this facing-the-viewer (FTV) bias has a sociobiological explanation: Mistaking an approaching human as retreating when he/she is actually approaching is assumed to be more costly than making the opposite mistake. Indeed, there appears to be support for this, as observers tend to have greater FTV biases for male walkers than for female walkers (Brooks et al., 2008; Schouten et al., 2010). We have also observed positive correlations between anxiety and FTV biases in our lab (Heenan et al., 2012). The goal of this study was to investigate whether physical exercise, which is known to reduce anxiety, would significantly reduce FTV biases for SFWs. We employed a 3 (Stimulus Type: full SFW, bottom-half-only, top-half-only; within-subjects) x 3 (Exercise Condition: standing, walking, or jogging on a treadmill; between-subjects) mixed design. We hypothesized that physical exercise would decrease FTV biases for the full SFWs only, as bottom-half- and top-half-only SFWs carry less sociobiological relevance than full SFWs. Sixty-six participants completed anxiety questionnaires, performed the treadmill task (10 min), and then immediately completed the SFW task. As hypothesized, physical exercise reduced FTV biases for the full SFW stimuli only. Furthermore, anxiety (measured before the treadmill task) was significantly correlated with FTV biases for the standing condition only. Our results suggest that the FTV bias for biological motion stimuli may indeed have a sociobiological basis.